Use the Diagram of an Action Potential to Answer the Following

Multiple Choice

Use the diagram of an action potential to answer the following questions.

-Phase 0 of the action potential shown is produced by an

A) inward $\mathrm{K}^{+}$ current
B) inward $\mathrm{Na}^{+}$ current
C) inward $\mathrm{Ca}^{2+}$ current
D) outward $\mathrm{Na}^{+}$ current
E) outward $\mathrm{Ca}^{2+}$ current